Multiple antibody detection in 'seronegative' myasthenia gravis patients.

BACKGROUND AND PURPOSE: Myasthenia gravis (MG) is an autoimmune disease caused by antibody mediated impairment in the neuromuscular junction. Seronegative MG (SNMG) without antibodies against acetylcholine receptor (AChR) and muscle-specific kinase (MuSK) by routine assays accounts for about 20% of all MG patients. METHODS: Plasma from 81 Chinese MG patients previously found to be seronegative was tested by routine assays for AChR and MuSK antibodies. These samples were screened by (i) a novel, highly sensitive radioimmunoassay for AChR antibodies; (ii) cell-based assays for clustered AChR, MuSK and lipoprotein receptor-related protein 4 (LRP4) antibodies; (iii) a radioimmunoassay for titin antibodies. RESULTS: Antibodies to AChR, MuSK, LRP4 and titin were found in 25% (20/81), 4% (3/81), 7% (6/81) and 6% (5/78) of SNMG patients, respectively. In total, 37% of SNMG patients were found to be positive for at least one of the tested antibodies. AChR antibody positive patients had more severe disease (P = 0.008) and a trend towards fewer remissions/minimal manifestations than AChR antibody negative patients. The four patients with coexistence of antibodies had more severe disease, whilst the seronegative patients had milder MG (P = 0.015). CONCLUSIONS: Detection of multiple muscle antibodies by more sensitive assays provides additional information in diagnosing and subgrouping of MG and may guide MG treatment.

Relieving effect of Artemisia argyi aqueous extract on immune stress in broilers.

This experiment aimed to investigate the relieving action of Artemisia argyi aqueous extract (AAE) on immune stress in broiler chickens. A 2 × 2 factorial design was used to test the effect of 2 dietary treatments (adding 0 or 1000 mg/kg AAE) and 2 immune stress treatments (injecting saline or lipopolysaccharide (LPS)). A total of 96 one-day-old Arbor Acres (AA) broilers were randomly divided into four treatment groups with six replicates, four birds in each replicate. Broilers in Treatment groups 1 and 2 were fed with the basal diet, and those in Treatment groups 3 and 4 were fed with the experimental diet supplemented with 1000 mg/kg AAE. On days 14, 16, 18 and 20, broilers in both Treatments 1 and 3 were injected intra-abdominally with LPS solution at the dose of 500 µg LPS per kg BW with the LPS dissolved in sterile saline at a concentration of 100 µg/ml, and those in Treatments 2 and 4 were injected intra-abdominally with equal amount of sterile 0.9% saline. Blood samples were collected on days 21 and 28. The results showed that dietary supplementation of AAE prevented reductions in average daily gain (ADG) and average daily feed intake (ADFI) of broilers caused by LPS on d 15-21. On day 21, the injection of LPS increased serum adrenocorticotropic hormone (ACTH) and corticosterone (CORT); meanwhile, feeding AAE reduced the rise of CORT caused by LPS. Immune parameters such as interleukin-1 (IL-1), interleukin-2 (IL-2), interleukin-6 (IL-6), immunoglobulin G (IgG) and immunoglobulin A (IgA) were also improved by LPS, but the content of IL-2 and IgG in broilers fed with AAE diet was significantly lower than that of broilers fed with control diet. All the data suggested that diets supplemented with AAE could relieve the immune stress response of broilers.

GR gene polymorphism is associated with inter-subject variability in response to glucocorticoids in patients with myasthenia gravis.

BACKGROUND AND PURPOSE: Glucocorticoids (GCs) are the mainstay treatment of myasthenia gravis (MG). However, wide inter-individual variability exists in the response to GCs. METHODS: A Chinese cohort of 257 MG patients treated with GCs was evaluated for the association between 19 single nucleotide polymorphisms in the GR gene and clinical response to the initial 3 month GC therapy. A quantitative MG score decreasing by ≥3 units or becoming zero was defined as sensitivity to GCs. RESULTS: The rs17209237* G allele was less frequent in the GC insensitive group compared with the GC sensitive group [P = 0.013, odds ratio (OR) 0.119]. The rs9324921* A allele was more frequent in the GC insensitive group than in the GC sensitive group (P = 0.046, OR 1.94). Carriers of the rs17209237 G allele were less frequent in the GC insensitive group than in the GC sensitive group (dominant model, P = 0.009). Carriers of the rs9324921 A allele were more frequent in the GC insensitive group than in the GC sensitive group (dominant model, P = 0.037). Multivariate logistic regression revealed that the rs17209237 G allele carrier (P = 0.037, OR 0.12) and disease duration before GC treatment (P = 0.011, OR 3.45) were independent factors that contributed to GC efficacy. CONCLUSION: rs17209237 in the GR gene was identified as an independent factor that contributes to GC efficacy in MG patients. The genetic variations of the GR gene may play a role in predicting response to GC treatment.

TNF alpha inhibits myogenic differentiation of C2C12 cells through NF-κB activation and impairment of IGF-1 signaling pathway.

Cachexia or muscle wasting is a common condition that occurs in many chronic diseases. The wasting conditions are characterized by increased levels of TNF-α which was also known as cachectin in the past. But how TNF-α exerts its cachetic effects remains controversial. To clarify this issue, we investigated the impact of TNF-α on C2C12 cell myogenic differentiation. Our results demonstrate that myotube formation was completely inhibited by TNF-α when added to differentiating C2C12 myoblasts. The inhibitory effect of TNF-α on differentiation was accompanied by activation of NF-κB and down regulation of myogenin and Akt. Importantly, TNF-α's effect on differentiation was abolished when IGF-1 was added to the culture. IGF-1 treatment also inhibited NF-κB reporter activity and restored Akt levels. Our data suggest that TNF-α inhibits myogenic differentiation through NF-κB activation and impairment of IGF-1 signaling pathway. The reversal of TNF-α induced inhibition of myogenesis by IGF-1 may have significant therapeutic potential.